Belief in God is as natural as any instinct can be. An atheist asked Imam Ja'far Sadiq (a.s.) how could he convince him about the existence of God? Coming to know that the man had gone several times on sea voyages, Imam (a.s.) asked him: "Have you ever been caught in a fierce storm in middle of nowhere, your rudder gone, your sails torn away, trying desperately to keep your boat afloat?" The answer was, 'yes'. Then Imam (a.s.) asked: "And sometimes perhaps even that leaking boat went down leaving you exhausted and helpless on the mercy of raging waves?" The answer was again, 'yes'.

Then Imam (a.s.) asked: "Was not there, in all that black despair, a glimmer of hope in your heart that some unnamed and unknown power could still save you?" When he agreed, Imam (a.s.) said: "That power is God."

We think about thousands and thousands of things. We imagine a horse, a man, an aero plane, the earth, a train and a book. We see the pictures of these things displayed on the screen of our imagination.

This is called the existence in imagination (Wujud-e-Dhehni).

And also a horse, a man, an aero plane, the earth or a book has its own existence outside our imagination. That is called existence outside imagination. This is the real existence (Wujud-e-Khariji).

Sometimes, we imagine such ideas, which can never be found, outside our imagination. We may imagine "2+2=5" but can 2+2 be 5 in real existence? No. We may imagine that a thing exists and also does not exist at the same place at the same time. But can this happen in the world of reality? Certainly NOT.

Such imagined ideas, which can never exist in reality, are called (Mumtaniul-wujud) 'impossible'.

Also we imagine a man walking at certain time. Can this happen in reality? Remove all other ideas from your mind. Just look at the imagined picture of that man walking at a particular time. Now say, is it necessary that the man should be walking at that time? Or, on the other side is it impossible of him to be walking at that time? The answer to both questions is 'No'. Why? Because it is neither essential nor impossible for any man to walk at a given time. He may be walking; he may not be walking. So far as the reason and logic is concerned both his walking and not walking are possible - possible but not necessary.

Such imagined ideas, which have equal relation with existence and non-existence, are called (Mumkinul-Wujud) Possible or Transient. They may exist in reality; they may not exist. There is nothing in their nature to demand this or that. So for as their nature is concerned, 'To be' and 'Not to be' both are equal to them.

So far we have seen two categories of relationship between an imagined idea and its existence in reality.

(1) Where that idea has equal relation with existence and non-existence. It may exist; it may not exist. There is nothing in its nature to prefer either side. (2) Where that idea can have absolutely no relation with existence. It, by it very nature, is non-existent.

It will appear from above classification that there should be a third category which would be opposite of 'Impossible' (Mumtaniul-Wujud) mentioned in (2) above. This third category is of the idea, which can have absolutely no relation with non-existence. By its very definition, it is self-existent. Such an idea is called (Wajibul-Wujud) 'Essential Existence' or 'Absolute Existence.'

There is much conflict between the points of views of atheists and those who believe in a Supreme Being, Who created the world. Still there is one important point where both are in complete agreement.

Both agree that the basic source or cause of the universe is Eternal - has no beginning and no end; was always and will remain forever. In other words it is self- existent or 'Wajib-ul-Wujud'.

The reason for this idea is very simple: As every thing in this universe falls under the category of Mumkinul-Wujud 'Transient', it has equal relation with existence and non-existence. Once these things did not exist; now they exist; sometime in future they will cease to exist. By their nature they cannot demand to exist or to cease to exist. Therefore there MUST be a source or cause to bring them to existence or to terminate their existence.

And (it is the important point) that source or cause should not itself be just a 'Transient'; otherwise it will itself need a source or cause to bring it into existence. And this chain of cause and effect MUST stop on cause which needs no outside source or cause for its existence. It means that the final source or cause of bringing this universe into existence MUST be 'self- existent'.

It is interesting to note that even the atheists accept this point, because they say that nothing can come out of nothing and therefore the basic source of existence must be eternal. It is from ever and will remain forever.

Now comes the first difference. The atheists say that that eternal source of existence is 'Matter'. The believers say that that eternal source of existence is God.

We will discuss it afterwards. Here it is enough to establish a common ground of belief, and that is the faith that the basic source or cause of the existence of the universe is Eternal- without beginning and without end.